In this paper the authors observed the pathological alterationsin lamina propria of seminiferous tubules from 41 patients witholigospermia and azoospermia by using morphometry and immuno-histochemistry. Morphological alterations in seminiferous tubules ofthese patients were classified into three types; hypospermato-genesis, spermatogenic arrest and Sertoli-cell-only syndrome. Thelimiting membrane of the seminiferous tubules was found thicker invarious degrees. Morphometrically, there were significant differ-ences between the three types of alterations in terms of thickness ofthe lamina propria and the diameter of the seminiferous tubules.Immunohistochemically, the inner and outer layers of the laminapropria were positive for type Ⅳ collagen and laminin, while theintermediate layer, the hyperplastic zone, was negative, but thiszone was positive for type Ⅰ and Ⅲ collagen. The results indicatedthat the basic component of the altered lamina propria was of colla-gen fibers but not of type Ⅳ collagen, and In this paper the authors observed the pathological alterations in lamina propria of seminiferous tubules from 41 patients witholigospermia and azoospermia by using morphometry and immuno-histochemistry. Morphological alterations in seminiferous tubules of these patients were classified into three types; hypospermato-genesis, spermatogenic arrest and Sertoli- The limiting membrane of the seminiferous tubules was found thicker invarious degrees. there are significant differ-ences between the three types of alterations in terms of thickness of the lamina propria and the diameter of the seminiferous tubules. Immunohistochemically, the inner and outer layers of the laminapropria were positive for type Ⅳ collagen and laminin, while the intermediate layer, the hyperplastic zone, was negative, but thiszone was positive for type I and III collagen. The results indicated that the basic component of the altered lamina propria was of colla-gen fibers but not of type Ⅳ collagen, and